Squashed 'third_party/eigen/' content from commit 61d72f6

Change-Id: Iccc90fa0b55ab44037f018046d2fcffd90d9d025
git-subtree-dir: third_party/eigen
git-subtree-split: 61d72f6383cfa842868c53e30e087b0258177257
diff --git a/doc/examples/QuickStart_example2_dynamic.cpp b/doc/examples/QuickStart_example2_dynamic.cpp
new file mode 100644
index 0000000..ff6746e
--- /dev/null
+++ b/doc/examples/QuickStart_example2_dynamic.cpp
@@ -0,0 +1,15 @@
+#include <iostream>
+#include <Eigen/Dense>
+
+using namespace Eigen;
+using namespace std;
+
+int main()
+{
+  MatrixXd m = MatrixXd::Random(3,3);
+  m = (m + MatrixXd::Constant(3,3,1.2)) * 50;
+  cout << "m =" << endl << m << endl;
+  VectorXd v(3);
+  v << 1, 2, 3;
+  cout << "m * v =" << endl << m * v << endl;
+}